/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
 class Solution {
    public:
        ListNode* removeElements(ListNode* head, int val) {
            ListNode * dummyHead = new ListNode(0);
            dummyHead->next = head;
            ListNode * cur = dummyHead;
            while(cur->next != nullptr){
                if (cur->next->val == val){
                    ListNode * tmp = cur->next;
                    cur->next = cur->next->next;
                    delete tmp; 
                } else {
                    cur = cur->next;
                }
            }
            head = dummyHead->next;
            delete dummyHead;
            dummyHead = nullptr;
            return head;
        }
    };